Apparatus for projecting light rays



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EDWARD W. BOERSTLER, OF WATERTOWN, MASSACHUSETTS APPARATUS FOR PROJECTING LIGHT RAYS Application led November G, 1925. Serial No. 67,389.

The present invention relates to apparatus for projecting light rays.

The. usual forms of apparatus for projecting concentrated beams ot light possess the disadvantage that the retracting or transmitting medium by which the rays are 'focused or conducted can not be placed sutliciently close to the source ot" light to utilize the maximum intensity ot the rays emanating from the source. 'this is particularly true when the source consists otl an incandescent lamp which is usually formed with a bulb or envelope of considerable diameter and which, therefore, necessitates placing the refracting or transmitting medium at a distance from the incandescent filament at least equal to the radius of the bulb. Inasmuch as the intensity of light eniitted from the source varies inversely7 as the square of the distance from the source, the maximum intensity which the source is capable of giving is not utilized, a large portion of the light being dispersed before it enters the lens. Moreover, large projectors are open to the disadvantage that the proximity of the lens to the source is limited by the heat which is developed by the intense beam ot rays given ott by the source. llt is, therefore, necessary that the lens be placed at a sntticient distance from the lamp to avoid the destructive action of the heat and this results in a consideralgile diminution of the. intensity of useful light obtainable from a given lamp. The factor of heat generation is particularly important in such apparatus as motion picture projectors where the iilm must not be excessively heated, and also in apparatus for utilizing the therapeutic properties ot the rays ot the invisible spectrum. wherein the generation o t heat requires a limitation ot tho useful volume ot the desired rays.

rl`he objects ot the present invention are to provide an apparatus by which the light retracting or transmitting medium may be placed sutliciently close to the source of light to utilize the increased intensity of the rays, and also to provide tor the absorjition of the heat which may be generated by the intense concentration ot the emamitions from the source of light.

lVith these objects in view, one feature ot the invention comprises a source of light having a containing bulb or envelope which is formed with a depression extending toward the source of light and which is adapted to permit placing the reti-acting or conducting medium at a position close to the source. The depression not only serves the purpose of' permitting the retracting medium to be placed in a position of high concentration ot light rays, but also may be shaped to determine a lens shaped contour ot the refracting substance so that any desired optical eil'ects may be obtained.

Another feature of the invention consists in the employment of a liquid body whichv acts as the retracting medium for the lens and which surrounds the source of light in order that the heat generated may be absorbed. The liquid body is preferably of considerable magnitude in comparison with that ot the source, in order to permit a natural circulation by which' the most intense heat generated in the retracting portion of the medium may be carried oil' by convection currents and dispersed by radiation. Moreover, where natural circulation in the fluid body is insutlicient to provide the necessary cooling.

action, the construction permits a -forced circulation of liquid from an external source.

In the accompanying drawings. Fig. l is a sectional elevation showing one. form ot' apparatus embodying the features ot' the present invention: Fig. 2 a sectional elevation ot anioditied form of the invention shown in Fig. l; Fig. 3 is a trent view of the. incandescent lamp shown in Figs. l and 2; Fig. l is a side elevation ot' a torni ot' incandescent lamp employing a reflector; -Fig. 5 is a. trent elevation ot the lamp shown in Fig. l: Fig (i is an elevation ol a modified type of lamp; and Fig. T is a sectional elevation of an apparatus embodying the features of the present invention and employing a larbon are t'or the source ot light.

The invention is herein illustrated and described as embodied in projecting' apparatus employing two types ot light sources, one an ineamlescent lamp and the other a carbon arc. The incandescent lamp has its bulb formed with a dejiression to receive the refracting medium which ma7 be either liquid or ,solid to provide a lens at a. point ot intense concentration ot the light rays, it be ing preferred to employ a liquid re'tract'iug medium where a high candle power lamp is used in order to absorb the heat generated b v the tilament. The carbon are tvvpe ot' projcctor emplovs larhon electrodes which is surrounded b v a cooling` liquid in a suitable container which is tormed so aS to present lens shaped surfaces opposite the arc to contine. a portion ot' the retraeting medium of such shape as to give the desired tocus to the rays emitted b v the arc.

The apparatus shown in Fig. 1 comprises a source of light consisting ot' an incandescent. lamp having a filament 8 and a glass bulb or envelope 10. l`he envelope is t'ornied with a depression 11 either b v molding or blowingaccording to anv usual or preferred method. The. depression is formed so that the wall of the bulb at that point extends Sutlicientl)Y close to the iiiament: to utilize the high concentration of light ravs emanating therefrom. This depression may be spherical in contour or ot anv shape which in combination with the rclracting medium will produce the desired lena etlfect. The retracting medium comprises a large bodv ot' liquid 12 received in a chamber 14, having a cover 1G upon which the lamp is supported. A portion ot the retracting medium opposite the filament is contined between the depression 11 and a transparent leus member 1S to determine a lens shaped portion ot the retracting medium. The. lens member 1S ifs secured to a mounting` sleeve 2O bv' screws Q2 and the sleeve iS threaded on a nipple 21 ot' the chamber. The lens member 1S may be ot an)r desired shape to cooperate with the depression 11 depending on thc 1.et"ractiug action desired to be imparted to the rays .so that the retracting e'llect ot any ot the well known typesl of lenses may be obtained. The incan descent lamp is supported in the cli-unber b v means ol a pair ot upstanding brackets il() secured to the cover 'ttt and supporting a lamp socket which is indicated `generall)v at 3:2. The lamp extends downwardl \Y trom the socket through an opening Zit in the cover and is :sealed to prevent leakage ot tluid hy means oli a tlexible gasket. tt. 'l`he lamp ma)Y be placed in position b v removing the cover and inserting the bulb in the socket through the opening l-lso that the bulb is lirmlvv seated against the gasket t and the cover then replaced on the chamber. "the chamber is provided with inlet and outlet nipples 3S and -ttl to provide tor tilting with the liquid. rl`he nipples mav he closed bv caps 42 and tt as shown in Fig. 1 or niav be connected with a tluid .supply to maintain a forced circulation through the chamber.

The portion of liquid included between the 1,7oo,ooc

depression 11 ot the bulb and the lens nicmber 1S comprises a lens acting to retract the light rays emitted from the tilan'ieut. The body ot fluid 12 which in the total is large compared to that portion included between. the, dc]' ressiou 11 and the lens member 18 acts as a cooling Huid not only to absorb the heat; emanating from the filament in all directions. but also to set up a natural circulation bv convection currents to disperse the more intense heat generated in the lens portion ot the liquid body to all portions ot chamber where it ma)7 be dissipated by radiation. The provision tor a continuous forced circulation through the, chamber is useful where the lamp is of A@uch power that the generated heat can not be readilr dissipated by the natural circulation within the chamber. Inaamuch as the liquid is in direct Contact with the external wall ot the bulb, the retlection losses usuallv incident to passage of light across transition surfaces between media ot widely ditterent refractive indices are avoided.

The apparatus shown in Fig. 2 is especiali)7 useful for the generation and utilization ot the ravs of the invisible Spectrum which are ot high therapeutic value. The construction is similar to that illustrated in Fig. 1 with thel exception that an applicator 50 substituted for the lens member 18. rthe incandescent lamp ma)7 be operated so as to give ott1 rays which are rich in ultraviolet light by operating the filament slightly above rated voltage as described in the copending application ot Boerstler, Serial No. 33.446. tiled Wav 2S. 1925. The refracting ettect or" the liquid medium received in the depression 11 close to the tilament serves to give a high concentration of such ravs and the applicator 50 extending into the tluid medium collects the ravs and conducts them to anv desired point. IThe, applicator is, snpported b v means ot a threaded sleeve 52 which is received on the nipple 24. A gasket 5t is secured between the sleeve 52 and a cooperative sleeve 5G. and by closely engaging the applicator .'30 prevents leakage ot liquid. In order to Secure maximum therapeutic volume ot the invisible rays, both the applicator 50 and tho envelope of the lamp are,l

preferably ot a material. auch as quartz or borosilicate glass. which possesses marked conductive properties toward the invisible spectrum. Moreover the tluid medium 12 mav he ot a solution which is selectivelyY tranaparent to these rays So that the longer visible. ravs and the intra-red heat rays may be filtered out. tv vpical :solution which possesses such seleetivit)Y is an aqueous Solution of copper Sulphate.

The lamp shown in Figs. 1t and 5 comprises an incandescent lamp similar to that previousl)v described which is formed with a depression 11 extending adjacent and near to the filament. In order that the rays emitted from the opposite side ot the .filament may not be lost a reflector provided which serres to cause a 'further increase in light concentration on the retraeting medium reccivcd within the depression. A device of this type is useful, not only in large projectors but also in therapeutic work to obtain great volume ot ultra violet rays. The retiector is preferably ot nickel which has a high melting point and which is also highly reflective to rays ot the invisible spectrum. Its posit-ion within the bulb insuresl minimum diminution ot intensityr ot the short raya, which are therebyv required to pass onl.)T once through the wall ot. the bulb. Another modified form ot lamp is Shown in Fig. G wherein the rays ot light are to be directed axiall)7 ot the lamp. In thi@ torni, the depreQSion 110 is formed in the end of the lamp and extends in an axial direction toward the filament. This lamp, when supplied with a retracting iQnbetance in the depression. is especially suitable tor Some typesl ot searchlights where consti-notional details require a socket mounting in axial alignment with the desired direction of the beam ot light.

The apparatuS shown in Fig. 7 illustrates the application ot the present invention to a form oit lamp in which the Source ot light consists ot a carbon arc. The are is formed between carbon electrodes G2 and t-l which are completel)7 surrounded tor a considerable portion ot their length b v the retract-ing liquid llt) which is eontined within a chamber container Gti. 'the container formed opposite the are with leur; portions (3S and between which the tluid in confined to determine a lena at a position ot great intensity of light. rthe container maIv be entirel \V ot glane or quartz or may be ot metal with tran#- parent inerts tor the ieneI members GS and T0. AS in the conatruction previene-lv described. the container is 'formed with inlet and outlet nipples 'T2 and Tl which may be connected. it deSired, through pipes TG and 7S to etlect a torced circulation of fluid through the container'.

t. will be apparent that the preeentinvention providea a projection apparatua. by which the maximum intensity ot the light emanating trom the source nur v be utilized. and in uo caxe with a le rtrlutive generation ot' hat. 'lhe apparatnuV is simple and eailv c nu1trueted- Furthermore. it' in lcadilv adapted to ditl'erent usen. in that tht` retract-- ing charmteristica may be readil)y altered b v a change in the transpaieutv lena numbera which determine the contour ol` the retracting medium. and the selective transparencv or tiltering` action ma)Y be convenientl)` altered ln' a subetitntion ot' various liquids.

l'lfaving thus described the invention, what is claimed is:

l. An apparatusy t'or projecting light ra \,':\t

comprising an incaiulescent lamp having a bulb formed with a deprcs'sion extending close to the tilament o't the lamp in a position o'tl great intensity of light, a chamber in which the lamp is supported, and a liquid medium received in the chamber and in direct contact with the bulb and forming with the depression ot the bulb a lens tor focusing the rays ot light emitted by the lamp.

An apparatus for projecting light rays comprising an incandescent lamp having al transparent bulb formed with a lens shaped depression extending close to the filament ot the lamp in a poaition ot great intensityv ot light, a. tluid cooling medium surrounding the bulb and in direct contactI with the wall thereof. and a transparent lensl member cooperating with the depression in the bulb whereby the tluid between the depression and the transparent lens member forms a lens tor focusing the light rays emitted. from the i candeecent lamp. i

it. An apparatus tor projecting light rays comprising an incandescent lamp having` a transparent bulb termed with a lens Shaped depreesion extending clone to the filament ot the. lamp in a position of great intenaityv ot light. a fluid coolingl medimn Surrounding the. bulb and in direct contact with the wall there ot. and a transparent lens member cooperating with the depression in the bulb whcrebi1 the tluid between the depression and the transiliareut lens member forms a lens tor tocueing the light rays emitted trom the incaiuleacent lamp, and a. reflector arranged on the opposite iidc ot the source ot light from the depress-ion `tor concentrating the light ralvS on the lens.

il. An apparatus ttor projecting light ra'vnl comprising a chamber, an incandeecent lamp received within the chamber having a bulb provided with a depression extending close to the filament in a position et greatintcneity of light, a fluid cooling medium received in the casing and in direct Contact with the wall ot the bulb and having Selective tranSpar-enc),v toward a portion ot the spectrum, and a transparent member in t-he Caei ng coolvierating with the depreseion ot the bulb to detine a lens shaped portion of the liquid medium.

5. .\n apparatue tor projecting light rays comprising an ine-unlescent lamp having a transparent bulb formed with a lepre. ion` a tluid cooling .medium lurrouiuling` the bulb in direct wntaet with the wall thereof and received in the depreaeion to term a lens. and a retlector ha ving high reflection properties toward the invisible Spectrum received with in the bulb.

ti. .'\n apparatus `tor projecting light ra'vs comprisinfcg' a source of light. consisting ot an incaiulescent lamp having it bulb provided with a depression extending cloae to the tilament ot' the lamp in a position ot great intensit)v ot light.. a casing containing a tlnid g medoc-0 cooling; medium surrounding ille bulb, the criolinrgT medium being,V in direct Contact with the wall of the bulb, an applicator for directing and coiidueliingr the rays emitted by the 5 source to a desired point and arranged 0p- -posile to the depression of' the bulb, the fluid included between the depression and the applicator forming a lens ler the rays of light emitted by the source. 1G 7. An apparatus for Droject-ing light rays col'i'iprising an incandescent' lamp having a filament and a bulb provided with a lens shaped depregsion extendingr close to the lilalnent in a position of great inl'enSity of light, 15 and a fluid cooling and mii-acting medium .surroimdingthe bulb in direct Contact with the. Wall thereof and fillingr the depression to forni a lens.

In testimony whereof l have Signed my 20 name to this specification.

EDYA HD lV. BOE STLliR. 

